The present invention relates to motors and more particularly relates to a motor-driven assembly with a motor unit and a working machine.
Assemblies of this type are principally known in the art and serve for various purposes of application. German patent application No. 43 15 826, for example, discloses a motor-and-pump assembly wherein an electric motor is flanged to a housing for a high-pressure pump. The rotor with its motor shaft engages into a recess of the housing 1 and has an eccentric which acts upon slidable pump pistons. The motor shaft is supported by way of respectively one bearing in the housing on each side of the eccentric. In addition, the electric motor still includes a third bearing in the area of the bottom of the bowl-shaped electric motor housing. The large overall length of the assembly is disadvantageous. Also, the electric motor in this assembly is required to overcome a great amount of frictional work because a large number of bearings are used and, besides, a large friction radius is produced due to the necessary bearing diameter.
Other assemblies have become known meanwhile wherein the motor shaft is mounted on only one side close to the motor. These assemblies suffer from the drawback, however, that the free end of the motor shaft is not supported in a sufficiently rigid manner so that oscillations and vibrations of the motor shaft are introduced directly by way of a bearing into the pump housing. Therefore, an object of the present invention is to provide a motor-driven assembly which permits a flexurally resistant mounting support of the motor shaft along with a smallest possible axial mounting space and a low weight.
This object is achieved by the provision of a holding element which extends through the motor shaft and on which the rotor is pivotably mounted. This measure ensures a reliable mounting support of the motor shaft and a small axial overall length.
Preferably working machine is configured as a pump with a pump housing, and the supporting holding element extends through at least part of the pump housing. The result is that the holding element is also supported on the pump housing.
In a preferred embodiment holding element supports the pump eccentric which is unrotatably connected to the motor shaft. Thus, both the motor shaft and the pump eccentric is supported by the pivot.
In a preferred aspect of the present invention, the motor shaft is tubular and pivotably mounted on the axle, with bearing elements interposed. The bearing elements arranged between the motor shaft and the axle have a small friction radius and thereby cause especially little frictional work. In addition, the bearing elements dampen vibrations.
In a preferred aspect of the present invention, a bearing element is arranged so as to be in alignment with a commutator in a radial direction. This measure permits utilizing the space available radially in the area of the commutator in a manner so that the axial overall length of the assembly can be shortened to a great degree. In connection therewith, it is also possible to arrange a bearing element so as to be aligned with a rotor winding in a radial direction. This is done, for example, in the area of the bottom of the bowl-shaped motor housing and also shortens the axial overall length.
In an embodiment of the present invention, the axle is mounted with a first bearing in a bore of the pump housing and with a second bearing on a bottom of a motor housing. Further, the bearing elements of the motor shaft and the pump eccentric are arranged between the bearings of the axle so that the forces are applied between the bearings of the axle. These measures ensure a reliable end-sided support of the holding element without force application at a freely projecting end.
In an embodiment of the present invention, the axle bears with a collar against the bottom of the motor housing and is supported indirectly or directly under tensile stress on the housing. These features permit the attachment of the drive unit on the housing by means of the axle, without the necessity of additional or separate attachment elements.